Very small array blog has really neat charts visualizing the genres of music that dominate the top record charts over the years. This one above shows how pop ruled the '60s (only to be replaced by rock in the '70s, '80s, and '90s - then you'll see the rise of urban music in the '90s and '00s): Link - via Cool Infographics

I have heard of a theory that "Popular" music runs in a cycle, loosely related to the economic mood of the time, and a 13 year or so cycle. The more positive the economic mood, the more upbeat pop is popular, the lower the economic mood, the more heavier an punky sounds are popular. A good example is the 1990s, which as an economic downturn peaked, so did the popularity of Grunge and the Madchester scene. As the economy picked up in the late 90s, "pop" became popular, with the rise of BritPop and a number of Boy Bands, and that scene waning as the economy turned down in the early 00s.

Isn't 'pop' whatever's most popular at the time? And what exactly is Urban if there's already categories for R&B, Hip Hop, Rap, Club, Teen Pop, Pop, Pop Rock, Alt Pop, Pop Pop, and Pop Diggety Pop? But very interesting to see how monotonous the music industry has become..the ones that are recorded at least.